Resin molded products in specific shapes are made from thermoplastic resins by various common processes, such as injection molding, blow molding, extrusion molding, and press molding.
Patent Document 1 discloses a process for obtaining a resin molded product made of a thermoplastic resin by vacuum cast molding using a rubber mold, wherein the thermoplastic resin is selectively heated in preference to the mold. In the resin molding process, when the thermoplastic resin in a molten state is filled into the cavity of the mold, the thermoplastic resin is irradiated with electromagnetic waves having wavelengths ranging from 0.78 to 2 μm through the mold, whereby the thermoplastic resin is more strongly heated than the rubber mold, based on the difference of the physical properties of the rubber composing the mold and the thermoplastic resin.
However, when a thermoplastic resin is molded using a rubber mold, additional means may be necessary for improving the properties such as shape and surface accuracy of the resin molded product. In particular, when the resin molded product to be molded is large or thin-walled, or the thermoplastic resin material used for molding has a high viscosity, mold cavity filling may be so difficult that it requires additional means for improving the above-described properties.
Alternatively, for example, Patent Document 2 discloses a powder slush molding process, including attaching a powder slush material in a powdery state to the faces of a die and melting it to an intended thickness, and then cooling the material thereby molding a resin molded product adhered to the die. However, Patent Document 2 includes no description about the problem to be solved by the present invention, or the difficulty in increasing the filling pressure of a thermoplastic resin filled into a rubber mold, and thus includes no means for improving the above-described properties.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-216447    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2000-254930